A decoloring apparatus or a MFP (Multi-Function Peripheral) having a decoloring function, which is capable of decoloring a developed color of a toner by applying heat, is known. These apparatuses need to prevent the color of the toner froth remaining after decoloring in any coverage rates. Therefore, it is necessary to determine various performances such as a set temperature, of a heat source targeted at a paper having highest coverage rate and a processing speed of the paper (for example, refer to Japanese unexamined Patent Application Publication No. 2016-212432).